Difference between revisions of "What the JVM needs"
From JVMLangSummit
Jump to navigationJump to searchLine 14: | Line 14: | ||
=== storage management === | === storage management === | ||
* floating garbage foo(o, o=null); is tailcall a solution? | * floating garbage foo(o, o=null); is tailcall a solution? | ||
+ | * concurrent collection of permgen | ||
=== limits === | === limits === | ||
Line 22: | Line 23: | ||
=== types === | === types === | ||
* structs (efficient pointerless element selection) | * structs (efficient pointerless element selection) | ||
− | * value types (no mutability, acmp-identity, id-hashcode, monitorenter | + | * value types (below) |
− | * immutable arrays = array-like value types | + | |
+ | === value types === | ||
+ | no mutability, acmp-identity, id-hashcode, monitorenter | ||
+ | * immutable arrays == array-like value types | ||
+ | * issue: intermediate early array construction states interact with memory model | ||
+ | * perhaps need a typestate distinction: under construction vs. immutable |
Revision as of 11:52, 28 July 2010
Contents
Notes from Rich Hickey's workshop
user mode limitations
- please optimize this
- fences
- typestate: now immutable - especially arrays (typically encapsulated in non-writing header, a la java.lang.String)
- Why Tailcalls: as a guarantee, not just an optimization
numbers
- fixnums
- need a uniform entry/exit types (Object => boxing)
- Hacker's delight overflow detection is OK (only for add/sub); need a static method that throws overflow-exception?
storage management
- floating garbage foo(o, o=null); is tailcall a solution?
- concurrent collection of permgen
limits
- 31-bit arrays
- 16-bit instructions
- static data structures (array literals)
types
- structs (efficient pointerless element selection)
- value types (below)
value types
no mutability, acmp-identity, id-hashcode, monitorenter
- immutable arrays == array-like value types
- issue: intermediate early array construction states interact with memory model
- perhaps need a typestate distinction: under construction vs. immutable